Estimated Prevalence of Nonverbal Learning Disability Among North American Children and Adolescents

"Picture this from there": spatial perspective-taking in developmental visuospatial disorder and developmental coordination disorder

Introduction

Either Developmental Visuospatial Disorder (DVSD) and Developmental Coordination Disorder (DCD) present with difficulties in visuospatial processing, even though entailing different degrees of impairment. Among the visuospatial domain, spatial perspective taking is essential to interact with the environment and is significantly involved in many daily activities (e.g., environment navigation and spatial orienting). Notwithstanding, no previous studies have investigated this spatial domain in children with DVSD and limited evidence is available regarding DCD. Consistent with a transdiagnostic approach, the first goal of the present study was to compare spatial perspective taking abilities of these groups, also including a control group of not diagnosed peers (ND). Secondly, the role of different fine-motor and visuo-spatial predictors on the spatial perspective taking performance was considered.

Method

A total of 85 participants (DVSD = 26; DCD = 26; ND = 33), aged between 8 and 16 years old, were included in the study. Tasks assessing spatial perspective taking, fine-motor, visual imagery, and mental rotation skills, as well as visuo-spatial working memory were administered.

Results and Discussion

Overall, our results confirmed weaknesses in spatial perspective taking in both clinical groups, with the DVSD obtaining the lowest scores. Similarities and differences in the predictors accounting for the performance in the spatial perspective taking task emerged, suggesting the possible employment of different fine-motor or visuospatial strategies by group. Findings are discussed considering the potential impact they may have both in research and clinical practice.

Estimating the prevalence of Non-Verbal Learning Disability (NVLD) from the ABCD sample

Non-Verbal Learning Disability (NVLD) is a neurodevelopmental disorder characterized by deficits in processing visuospatial information but with age-appropriate verbal skills. This cognitive profile has been hypothesized to be associated with atypical white matter, but at the present there is a lack of evidence for this hypothesis. Currently, the condition is not characterized within the main diagnostic systems, in part because no clear set of criteria for characterizing the disorder exists. This report is the first attempt to estimate NVLD prevalence, using two sets of diagnostic criteria, in a large sample of over 11,000 children who were selected without regards to problems of specific nature, either psychological, neurological, physical and/or social. Furthermore, it examined the association between the profile of cognitive abilities and aspects of whole-brain white matter measures in children with and without symptoms associated with NVLD. Participants were drawn from the Adolescent Brain Cognitive Development (ABCD) study, a 10-year longitudinal study of 11,876 children in the U.S. The data used in the present study were drawn from the initial testing point at which the children were 9-10 years old. Prevalence of NVLD based on two distinct sets of criteria, correlations between the measures used to create the criteria, correlations between criteria measures and measures of white matter integrity. The cognitive criteria included measures of visuospatial processing, reading, intelligence and social skills. By varying the cut-offs applied to social skills in conjunction with visuo-spatial difficulties, spared reading skills and intelligence scores, we calculated prevalence for two NVLD groups. White matter characteristics were measures of volume, fractional anisotropy and mean diffusivity. Based on the criteria used, the estimated prevalence of NVLD varied from 1 to 8%. Furthermore, children with NVLD showed a dissociation between measures of visuo-spatial processing not observed in non-NVLD children. At the neurological level, findings provide preliminary evidence of associations between the cognitive profile of NVLD and abnormalities in white matters tracts. The present study documents that exists, within this large non-selected sample, a proportion of youth who show evidence of NVLD. Given those results, it appears essential to establish the best diagnostic criteria, to improve the treatment options and quality of life for children with this disorder.

Modified Approaches to Treating Anxiety for Children With Visual-Spatial Problems: A Strengths-Based Perspective

Anxiety disorders are common and impairing1 and affect as many as 30% of youth with2 and without3 neurodevelopmental disorders. Nonverbal learning disability (NVLD) is an understudied neurodevelopmental disorder with an estimated prevalence of 3% in North American children and adolescents.4 Although definitions of NVLD vary, all include a core deficit of difficulty with visual-spatial processing. Importantly, anxiety is also a common psychiatric comorbidity for youth with NVLD, affecting roughly one-third of these youth.4,5 In youth with neurodevelopmental disorders, treatment is often sought or received for comorbid conditions (eg, anxiety, attention-deficit/hyperactivity disorder) or associated impairments, rather than for the symptoms or core deficits of the neurodevelopmental disorder itself.6 Considerable work has examined the adaptation of anxiety disorder treatments for children with attention-deficit/hyperactivity disorder7 and autism.8 Comparatively little work has explored treatment approaches for children with NVLD. Given the overlap of anxiety symptoms and visual-spatial problems in NVLD,9,10 herein we consider how these cognitive problems might interfere with patients' abilities to engage with common treatment approaches.

External Validation of BMT-i Computerized Test Battery for Diagnosis of Learning Disabilities

Background: Learning disabilities (LDs) are a major public health issue, affecting cognitive functions and academic performance for 8% of children. If LDs are not detected early and addressed through appropriate interventions, they have a heavy impact on these children in the social, educational, and professional spheres, at great cost to society. The BMT-i (Batterie Modulable de Tests informatisée, or "computerized Adaptable Test Battery") enables fast, easy, reliable assessments for each cognitive domain. It has previously been validated in children ages 4-13 who had no prior complaints. The present study demonstrates the sensitivity of the BMT-i, relative to reference test batteries, for 191 children with cognitive difficulties. Materials and Methods: These 191 subjects were included in the study by the 14 pediatricians treating them for complaints in five cognitive domains: written language [60 (cases)]; mathematical cognition (40); oral language (60); handwriting, drawing, and visuospatial construction (45); and attention and executive functioning (45). In accordance with a predefined protocol, the children were administered BMT-i tests first, by their pediatricians, and reference tests later, by specialists to whom the BMT-i test results were not disclosed. Comparison of BMT-i and reference test results made it possible to evaluate sensitivity and agreement between tests. Results: For each of the five domains, the BMT-i was very sensitive (0.91-1), and normal BMT-i results were highly predictive of normal results for specialized reference tests [negative likelihood ratio (LR-): 0-0.16]. There was close agreement between BMT-i and reference tests in all domains except attention and executive functioning, for which only moderate agreement was observed. Conclusion: The BMT-i offers rapid, reliable, simple computerized assessments whose sensitivity and agreement with reference test batteries make it a suitable first-line instrument for LD screening in children 4-13 years old.

Contributions of Cerebellar White Matter Microstructure to Social Difficulty in Nonverbal Learning Disability

Emerging evidence suggests that the cerebellum may contribute to variety of cognitive capacities, including social cognition. Nonverbal learning disability (NVLD) is characterized by visual-spatial and social impairment. Recent functional neuroimaging studies have shown that children with NVLD have altered cerebellar resting-state functional connectivity, which is associated with various symptom domains. However, little is known about cerebellar white matter microstructure in NVLD and whether it contributes to social deficits. Twenty-seven children (12 with NVLD, 15 typically developing (TD)) contributed useable diffusion tensor imaging data. Tract-based spatial statistics (TBSS) were used to quantify fractional anisotropy (FA) in the cerebellar peduncles. Parents completed the Child Behavior Checklist, providing a measure of social difficulty. Children with NVLD had greater fractional anisotropy in the left and right inferior cerebellar peduncle. Furthermore, right inferior cerebellar peduncle FA was associated with social impairment as measured by the Child Behavior Checklist Social Problems subscale. Finally, the association between NVLD diagnosis and greater social impairment was mediated by right inferior cerebellar peduncle FA. These findings provide additional evidence that the cerebellum contributes both to social cognition and to the pathophysiology of NVLD.

Altered structure and functional connectivity of the hippocampus are associated with social and mathematical difficulties in nonverbal learning disability

The hippocampus is known to play a critical role in a variety of complex abilities, including visual-spatial reasoning, social functioning, and math. Nonverbal learning disability (NVLD) is a neurodevelopmental disorder characterized by deficits in visual-spatial reasoning that are accompanied by impairment in social function or mathematics, as well as motor or executive function skills. Despite the overlap between behaviors supported by the hippocampus and impairments in NVLD, the structure and function of the hippocampus in NVLD has not been studied. To address this gap in the literature, we first compared hippocampal volume and resting-state functional connectivity in children with NVLD (n = 24) and typically developing (TD) children (n = 20). We then explored associations between hippocampal structure, connectivity, and performance on measures of spatial, social, and mathematical ability. Relative to TD children, those with NVLD showed significant reductions in left hippocampal volume and greater hippocampal-cerebellar connectivity. In children with NVLD, reduced hippocampal volume associated with worse mathematical problem solving. Although children with NVLD exhibited more social problems (social responsiveness scale [SRS]) and higher hippocampal-cerebellar connectivity relative to TD children, greater connectivity was associated with fewer social problems among children with NVLD but not TD children. Such an effect may suggest a compensatory mechanism. These structural and functional alterations of the hippocampus may disrupt its putative role in organizing conceptual frameworks through cognitive mapping, thus contributing to the cross-domain difficulties that characterize NVLD.

The contribution of motor functions to academic achievement in primary school: State of the art and future directions

This review is intended to point out the role played by motor skills proficiency in the academic achievement of typically and atypically developing pupils who are attending primary school. First, the interplay between motor and cognitive development will be presented. Next, the cognitive phenotype, not yet deeply investigated, of a neurodevelopmental condition associated with the atypical development of motor functions (known as Developmental Coordination Disorder) will be illustrated. Thus, the contribution of motor functions to academic learning and the impact of motor difficulties for pupils attending primary school will be discussed. In addition, the importance of developing observational tools to be used in educational settings and the need for effective interventions designed to empower motor functioning and academic achievement of atypically developing pupils with motor deficits will be highlighted. Finally, future directions within the educational agencies for the early detection of the atypically developing motor trajectories and their treatment will be traced.